New Floating Offshore Wind Farm to Generate Clean Energy for 45,000 People

[By: Sarens]

This is the first floating wind farm in France and is located 17 km off the Gulf of Fos, in the Marseille region.

Once inaugurated at the end of 2023, this wind farm will have three 8.4 MW turbines from Siemens Gamesa Renewable Energy, with an installed capacity of 25 MW.

Sarens was commissioned by Eiffage Métal for the lifting and assembling of the partsthat make up the pyramid-shaped structure and the floating buoys in which the electric turbine is placed, and on the load-out of the infrastructure onto the semi-submersiblebarge in which it travelled to its final location.

The new Provence Grand Large floating offshore wind farm, located 17 km off the Gulf of Fos in Marseille, will have an installed capacity of 25 MW when it’s commissioned at the end of this year, equivalent to the energy needs of 45,000 people in one year, as it will be composed by three 8.4 MW turbines manufactured by Siemens Gamesa Renewable Energy.

Sarens, world leader in heavy lifting, engineered transport and crane rental, and a major player in transport logistics and the installation of offshore wind farms around the world, was commissioned by Eiffage Métal to lift the various components of the three floating structures at the Fos-sur-Mer plant. To accomplish the task, Sarens sent to these facilities an LR1800 crane with a capacity of 800 tons, as well as a CC2500 with a capacity of 500 tons and 20 axle-lines of SPMTs. 

This installation, the first of its kind in France, will have three 45-metre-high pyramid-shaped structures on which each wind turbine will be placed. Manufactured by EiffageMétal at its facilities in Fos-su-Mer and based on a TLP design developed by SBM Offshore, these structures have a central buoy as well as two other submersible buoys at each end of the structure, between which an innovative system of fixing to the seabed using tensioned cables is placed.

Sarens’ team was responsible for lifting and assembling the central buoys of the three structures, in addition to the three central columns, the three transition pieces, the 18 lateral buoys, the 9 side nodes, as well as the anchorages of each of the pieces.

Once all the parts were assembled, weighing close to 2,800 tons, 45 metres high and 70 metres wide, Sarens was also involved in the second phase of the project, taking charge of weighing and loading the three floating foundations onto the semi-submersible barge on which they were to be transported to their final location 17 km off the coast of Marseille. 

On this occasion, Sarens used its K24STs arranged in two trains, as well as two 6-axle SPMTs for auxiliary work and four 30-metre MB1500x1000 modular beams to transport the floating structures over distances of between 50 and 150 metres to the quay wall. The team deployed to this location worked in two shifts to adequately keep pace with the vessel float-off operation until all three structures were fully loaded onto the barge.

The new Provence Grand Large floating offshore wind farm will be the first to come into operation on French soil, although in Europe they’re becoming more usual. For example, the Hywind Scotland wind farm, with a capacity of 30 MW and located 29 km off the coast of Peterhead in Scotland; WindFloat Atlantic, with 25 MW of installed capacity 20 km off the coast of Viana do Castelo in Portugal; or the Kincardine farm with 50 MW installed 15 km off the coast of Aberdeen in Scotland. 

In contrast to conventional offshore variants, floating offshore allows the more powerful and constant wind to be harnessed in deeper waters, where it would be more difficult and costly to install conventional turbines. They are also simpler to install and dismantle at the end of their useful life, and less aggressive to the seabed, as generally only smaller anchors are used.

Sarens has extensive international experience in the assembly and maintenance of wind farms. It is participating in installations in France such as Fécamp, Saint Nazaire, Provence Grand Large or more recently, in the lifting and transport work for the foundation bases of the new offshore wind farm in Saint Brieuc, off the Brittany coast, where it has been able to transport loads of more than 1,150 tons.